ABSTRACT/ PROJECT SUMMARY Longstanding practice has treated early childhood caries (ECC) primarily through surgical dental repair, reinforced by current payment systems, an approach that does not address the natural history of the disease or the oral hygiene and dietary behaviors that mediate its occurrence. Professional consensus on the value of ECC disease management is emerging but behavioral strategies remain largely unstudied among Hispanic children in the United States. The long-term goal of the proposed study is to reduce oral health disparities and inform a paradigm shift from a focus on treatment to one that also embraces prevention. It is known that using fluoridated toothpaste twice daily and consumption of a low cariogenic diet has both preventive and therapeutic value. What is not known is how to best translate the adoption and maintenance of salutary behaviors to populations at greatest risk. The proposed randomized controlled trial will evaluate the efficacy of a family focused behavioral intervention, MySmileBuddy, to reduce ECC progression in high-risk Hispanic preschoolers. We propose to recruit and enroll 858 two to five year-old children, all with ECC, along with their caregiver from pediatric medical clinics in northern Manhattan, New York City. Specific Aims are: (1) to assess MySmileBuddy's efficacy (versus control) to decrease ECC progression (defined as positive change in number of decayed, missing, or filled teeth (?dmft>0) or surfaces (?dfs>0)) measured 12-months post-randomization (and assessed again 24-months post-randomization); (2) to assess MySmileBuddy's efficacy (versus control) to enhance adoption of twice daily fluoridated toothpaste use and consumption of a low cariogenic diet; and (3) to assess causal pathways through which MySmileBuddy influences twice daily fluoridated toothpaste use and consumption of a low cariogenic diet. The proposed research is innovative and represents a departure from the status quo by shifting focus from treatment to prevention, shifting education from verbal instructions and written materials provided by dental professionals to using interactive Health Information Technology delivered by Community Health Workers, and capitalizing on general pediatrics practices as a conduit for promoting children's oral health. At the completion of this study, we will know the extent to which MySmileBuddy promotes parents' acquisition and maintenance of oral hygiene and dietary behaviors that reduce ECC progression in a high-risk population of Hispanic preschool children. Ultimately, such knowledge has the potential to reduce the number of children needlessly affected by this preventable disease.